The invention relates to foamed epoxies, and more particularly, to foamed epoxies prepared using a liquid anhydride as a foaming agent in the presence of tertiary amine catalysts or similar strong nucleophilic catalysis.
Foamed epoxies are normally produced via addition of physical blowing agents such as inorganic compounds that thermally decompose at low temperatures and produce gases, or via addition of low volatile liquids, such as freons or similar fluorinert compounds, that also result in gas formation and expansion during the exothermic epoxy cure. In comparison, polyurethanes are commonly cured using an in-situ chemical side reaction that produces gaseous CO2 during the cure reactions. This reaction is specific to the properties of isocyanates, the key molecular building block of polyurethanes, which form carbamic acids in the presence of water and then cleave off CO2. Due to the completely different types of epoxy curing reactions, an in-situ chemical foaming process similar to the standard and widely used polyurethane foaming reactions and process has so far not been described in the literature.